The present invention relates to piston pumps, particularly for conveying concrete mixes. In such pumps preferably two pump cylinders are arranged in a frame structure so that the cylinder axes extend in parallel to each other. Scavenging chambers are also arranged in the frame structure for cooperation with the respective pump cylinder. Each pump or conveying cylinder is substantially aligned axially with its respective hydraulic drive piston cylinder arrangement.
Swiss Pat. No. 372,927 discloses a pump of the type described above wherein the pump cylinder has flanges at both ends which are connected with the scavenging chamber at one end and to the pump housing or frame structure at the other end thereof. A similar pump cylinder mounting is also disclosed in German Pat. No. 940,198.
The described arrangement of the pump or conveying cylinder between the scavenging chamber and the pump or valve housing is used substantially uniformly in all prior art pumps of this type. Similar considerations apply to the arrangement of the hydraulic drive piston cylinder in axial alignment with the respective pump cylinder. The hydraulic piston cylinder drive is secured to that side of the scavenging chamber which is located opposite the pump cylinder.
Such simple systems have, however, in spite of their clear structure, the disadvantage that the forces effective on the piston cylinder drive are fully transmitted through the pump cylinders, through said flange connections, and through the scavenging chambers to the pump or valve housing or frame structure. Such forces may be within the range of 20 to 30 tons. Hence, it is necessary to statically dimension the scavenging chamber, or chambers, so that it will not be deformed by such forces. Also due to such forces or loads it is necessary to provide a large number of nuts and bolts for securing the above mentioned flange connections. The required dimensions and flange connecting means are expensive and involved to manufacture and it is time consuming, for example, to exchange the conveying or pump cylinders.